﻿/************************************************************************

   Extended Silverlight Toolkit

   Copyright (C) 2010-2012 Xceed Software Inc.

   This program is provided to you under the terms of the Microsoft Public
   License (Ms-PL) as published at http://extendedsilverlight.codeplex.com/license

   Please purchase a commercial version of this toolkit if you are using
   it in a commercial product. The commercial versions support the project,
   and also include more features for each control, priority support,
   source code, updates, removed watermark, and a proprietary license.

   Visit http://xceed.com and follow @datagrid on Twitter.

  **********************************************************************/

using System;

namespace Xceed.Silverlight.Data.Stats
{
  public class MinimumFunction : CumulativeStatFunction
  {
    public MinimumFunction()
      : base()
    {
    }

    public MinimumFunction( string resultPropertyName, string sourcePropertyName )
      : base( resultPropertyName, sourcePropertyName )
    {
    }

    protected internal override void Validate()
    {
      base.Validate();
      this.ValidateSourcePropertyName( 1 );
    }

    protected internal override void Reset()
    {
      m_min = null;
    }

    protected internal override void Accumulate( object[] values )
    {
      if( StatFunction.CanProcessValues( values, 1 ) )
      {
        object value = values[ 0 ];
        IComparable comparableValue = value as IComparable;

        if( comparableValue == null )
          throw new InvalidValueException( "MinimumFunction can only work with objects implementing IComparable." );

        if( m_min == null )
        {
          m_min = value;
        }
        else
        {
          if( comparableValue.CompareTo( m_min ) < 0 )
            m_min = value;
        }
      }
    }

    protected internal override void AccumulateChildResult( StatResult childResult )
    {
      IComparable comparableValue = childResult.Value as IComparable;

      if( comparableValue == null )
        throw new InvalidValueException( "MinimumFunction can only work with objects implementing IComparable." );

      if( m_min == null )
      {
        m_min = childResult.Value;
      }
      else
      {
        if( comparableValue.CompareTo( m_min ) < 0 )
          m_min = childResult.Value;
      }
    }

    protected internal override StatResult GetResult()
    {
      return new StatResult( m_min );
    }

    private object m_min;
  }
}
